Tricyclo(4.2.2.0.sup.2,5)dec-9-ene-3,4,7,8-tetracarboxylic dianhydride, a known compound, is the adduct of two moles of maleic anhydride and one mole of benzene. It has the structure: ##STR2##
It is known to react maleic anhydride with benzophenone in benzene solution by exposing the reaction mixture to direct sunlight to prepare tricyclo(4.2.2.0.sup.2,5)dec-9-ene-3,4,7,8-tetracarboxylic-3,4,7,8-dianhyd ride (D. Bryce-Smith, et al., Chem & Ind. (London) 1962, 2060). D. Bryce-Smith, et al., obtained 93% yield by exposing 14 g of maleic anhydride and 2.8 g of benzophenone in 265 ml of benzene in a Pyrex tube to direct sunlight for 72 hours. The tetraallyl esters of these compounds are reacted with a mercaptan and oxygen in the presence of a dye sensitizer under irradiation by visible light. The products, the title compounds, are tetraesters in which the ester moieties have been converted from --O--CH.sub.2 CH.dbd.CH.sub.2 to --O--CH.sub.2 --CH(OH)--CH.sub.2 --SO--R, i.e., beta-hydroxysulfoxide derivatives of the original allyl esters of tricyclo(4.2.2.0.sup.2,5)dec-9-ene-3,4,7,8-tetracarboxylic acid.
Beta-hydroxyalkylsulfoxides can be prepared by the method of Anderson, U.S. Pat. No. 3,247,258, which is incorporated by reference, wherein the mercaptan (or thiol), the olefin and oxygen are in contact at temperatures above 80.degree. C. Anderson indicates that with certain olefins and mercaptans such as indene, styrene and thiophenol, the reaction occurs by mixing the olefin and mercaptan first, with the oxygen being bubbled through the mixture thereafter. Other patents such as Oswald, et al., U.S. Pat. No. 3,043,824 and Goodhue, et al., U.S. Pat. No. 3,210,243, which are each incorporated by reference, disclose preparing beta-hydroxyalkylsulfoxides through (1) a co-oxidation route using a hydroperoxide or through (2) oxidation of the sulfide by means of hydrogen peroxide. Oswald indicates that the preparation of hydroperoxide products by olefin-mercaptan co-oxidation to the sulfoxide requires chain initiators, e.g., ultraviolet light and the addition of peroxide compounds (hydroperoxides). In the absence of such catalysts, some co-oxidation reactions have extremely long induction periods and are not practical to carry out. Goodhue teaches that preparation of the sulfoxide using hydrogen peroxide is a three-step synthesis through the sulfide which in turn is prepared from the mercaptan with epichlorohydrin. Fields, in commonly-assigned U.S. Pat. No. 4,040,921, incorporated herein by reference, teaches a one-step process for beta-hydroxyalkylsulfoxides by reacting an olefin and a thiol with oxygen in the presence of a dye sensitizer using visible light at a temperature from -10.degree. C. to 70.degree. C.
The object of this invention accordingly is to produce as new compounds the 3-sulfoxy-1,2-propylene glycols-1-esters of tricyclo(4.2.2.0.sup.2,5)dec-9-ene-3,4,7,8-tetracarboxylic acid. These compounds are useful as cosurfactants in enhanced oil recovery, as surfactants and biocides, and as hydraulic fluids when of sufficiently low molecular weight.